Rare was their own fault. Rare management decided to focus on Kinect, it was not a mandate from MS. Lionhead, again their own fault, years of useless projects that never amounted to anything. I am not sure what happened to Ensemble. Bungie didn't want to do Halo anymore and MS let them go do whatever they wanted.
There is keyboard/mouse support coming to Xbox, but they are not shy about making PC only releases, they announced Gears tactics at E3, PC only for now. Obsidian has made more than just PoE you know. Fallout NV, Stick of Truth, KotoR2, Alpha Protocol, all are or would be fine with controllers. Besides, from the Chris Avellone interviews I have seen Obsidian management is a bit of a mess (understatement?), they could use some actual help there.